Tape feed suppression mechanism



O 1951 ,E. F. WATSON 2,572,685

TAPE FEED SUPPRESSION MECHANISM Filed May 13, 1946 )Nl/ENTOR By E. 5 WA TS ON ATT R/VEY ac'iaes 3 cycles while such simulated start impulse condition endures, and accordingly to advance the cipher key tape a like number of steps. If there has been no transmission from the transmittin station at the time that one or more cycles of the deciphering signal generator are caused by the disturbance which simulated a start impulse, the key tape at the receiving station will be a corresponding number of steps ahead of the key tape at the transmitting station and signals thereafter received from the transmitting station will' not be correctly deciphered.

Heretofore the practice has been, when the receiving apparatus ceased to print intelligible copy and it was apparent that the cause of the failure was the occurrence of an out-of-phase condition of the cipher tape at the receiving station rela tive to incoming signals ciphered at the transinto its next cycle.

The cooperation between the manually operable member and the member which conditions the blocking lever to block the tape feed lever is of a single action character, so that even though the manually operable member is held in the op- 1 erated condition, the latch will be released and the blocking lever will be restored to unblocking mitting station, to notify the transmitting 'sta tion to cease transmitting, as by the transmission. of a=break signal, tosintercommunicatewith the transmitting station for the purpose of agreeing on like starting points in the cipher tapes, and to request the transmitting station .to retransmit asmuch of the message as had been received in unintelligible form. This procedure is wasteful of time and is particularly annoying in conference types of intercommunication in which information is interchanged telegraphically in much the same manner as in telephone conversations.

.In the majority of occurrences of out-of-phase conditions due to causes hereinbefore setforth, the magnitude of the out-of-pha'se condition is of the order of a stepor two and the cipher tape at the receiving station is ahead of the cipher tape at the transmitting station. Correction may be effected by suppressing feeding of the cipher tape at the receiving station while the distributor of the cipher signal generator at the receiving station operates in response to thereception of 1 condition. Thus it is necessary to release and reoperate the manually operable member for each desired tape feed suppression, and suppression occurs only in singlesteps. I V

For a complete understanding of the invention reference may be had to the single figure of the ciphered signals from the transmitting station.

Since it would be undesirable to overcorrect for o'u't-of-phase conditions, it is preferable to provide for single step correction which may be re-' peated if it is found that 'one step is insufficient. To provide for single step tape feed suppression, the present invention includes a manually operable member which, upon being operated, prepares a lever to be presented in blocking relation to the tape feed lever of the transmitter. In the tape transmitter-distributor to which th invention has been adapted tape feeding is effected by a pawl and ratchet mechanism, the tape feeding operation is positive and the return stroke of the tape feed lever is permissive. The positi e feed- 'ing operation is performe by acyc ically operable bail which also controls the ta e sensing mechanism. 1 The blocking lever, having been conditioned to block the ta e feeding lever, cannot come into blocking relation until the bail has performed'the positive ta e f e in g operation. When this operation has been pe fo med the blocking lever moves into blocking relation to the tape feed lever, thereby preventing the permissive return of the tape feed lever when the bail moves away from that lever. The mechanism includes a latch for holding the blocking l ver in the preparatory condition. A latch releasing lever is connected to the bail but is normally held out of position to engage the latch by the blocking lever itself. As the blocking lever moves into blocking position it conditions the latch releasing lever for en agement with the latch. However, the latch releasing lever will not release the latch until the next cyclic operation of the bail.

numeral ll designates the face plate of a :brush' type distributor. A brush arm l2 carried by a. shaft [3 has interconnected brushesl'4 inconductive engagement with the segmented rings care ried by the face plate. Shaft I3 is driven by motor [6 through friction clutch l1 and gears I8. Shaft l3 has secured thereto a stop disc l9, with which there cooperates a stop lever 2| controlled by electromagnet 22. When electromagnet 22 is energized lever 2l' is withdrawn from blocking relation to disc [9 and shaft I3 is released for rotation. Y Shaft l3 also has secured thereto a cam23 which has a single apex. A lever 24 pivotedat 26 is held in engagement with cam 23 by tension spring 21. In the rest position of cam 23 lever 24 is held in the extreme counter-clockwise positionas viewed from the upper end of pivot 26. At its foremost end the lever 24 is provided with an adjustable abutment screw 28 which isengaged by a depending arm 29 of a bail 3| pivoted at 32...A V

tension spring 33 holds arm 29 of bail 3| in engagementwith abutment screw 28. In the rest condition of cam 23 lever 24 holds bail 3| in extreme counter-clockwise position as viewed from the foremost end of pivot 32. j

Above the bail 3! a plurality of tape sensing levers 36 are pivotally supported on rod 31. .At their right-hand ends the levers 36 are provided with tape sensing pins 38 and at their left-hand ends are bifurcated, and the bifurcations are entered by transmitter contact levers 39 which are pivoted on rod 4! and are insulated from each other. Intermediate their ends the tape sensing levers 35 are provided with depending arms 42 which terminate below the upper edge of bail 3|. Tension springs 43 bias the tape sensing levers 36 in counter-clockwise direction to engage their depending arms 42 with the lefthand side of bail 3|. With shaft l3 at rest bail 3| holds tape sensing levers 36 in extreme clock? wise position.

Shaft 31 also pivotally supports a tape feed lever 43. This lever has a depending arm 44,

5 similar to thedepending-armsef tape sensing levers 36, which engages -bail 3I under the-iniiuence of biasing spring 46. 'At its-free end the tape-feed lever 43 pivot/allysupports a. pawl 4'1 which is urged into engagement with-a ratchet 48 by spring 49.- Ratchet 48 1s secured to a shaft 5| which also has secureclto it' -a tape feed wheel '52 having radiallyextending pins engageable with feed-perforations '50 in perforated tape '53 containing code perforations 55 which, in the case of a cipher signal gen erator associated with a receiving system, would be the deciphering core combinations.

' "jSignals 'incoming over" conductor 64, which may represent a telegraph line, or the output of a radio receiver; detector and'amplifien-are applied to and" operate receiving relay-62. -This relay has'its armature normally engaging the marking contact which connected to the negative terminal ofbattery 3-3. A conductive'path extends over conductors't l, 66, outer rest segment of the distributor, brushes I4 carriedby distributor arm l2, inner --restsegment of the distributor, conductor 6! and winding of start magnet 22 of the distributor'to the negative terminal of battery-58. ---The batteries 63 and $8 being connected in opposition, the winding of electromagnet 22 is not energized and lever 2| is released to the position in which it holds distributor shaft disc 19 arrested. Upon response ofu'eceiving relay 52- to the start impulse of a code combination which 'is' of spacing nature, the armature moves to the spacing contact which is grounded, causing-current to flow in the winding of electromagnet 2 2 which attracts lever 2|, thereby disengaging the lever from distributor shaft disc l;9-andpermitting the shaft to rotate. As the brushes leave the rest segments they interrupt the energizing circuit of electromagnet 22- which releases. By the time this occurs the arresting shoulder-on disc 19 has passed the end of lever -21 so that the lever cannot interfere with the rotation of disc l9 and the brushes continueto rotate. The inner ring of the distributor is continuous except for the rest segment and as soon as theinner brush leaves the rest segment itengages the continuous ring which is connected through the look-.- ing winding of receiving relay 62 to a potential divider which provides a potential at a value between negative battery and ground. Following departure from-the rest segment the outer brush engages a short segment which is connected over conductor "H and conductor 12 to. a point 7.3 at which the path divides, one path extending through resistor M, the other extending through the operating winding of relay 16, resistor 11, and resistor l8 toa point 19- at. which these paths rejoin and continue over conductor 64, the armature of receiving relay 62 and the spacing contact of the relay to ground. -With thepath extended as described, to ground, relay 76, which is a mixing or deciphering relay, operates its armature to spacing, whereby ground is connected to the armature of that relay, through the locking winding of the relay, to a potential divider providing apotential between negative and ground and through the winding of a repeating relay 8! to a similar potential divider. Relay 8! has its marking contact connected to battery and its armature connected through the winding of an electromagnet 82 to ground. Electromagnet 82 represents the selector magnet of .a teletypewriter' printer which may be of the type shown in Patent 1,904,164 granted April '6 is. 1932 to s.- Morton et a1. andthedisclosure of this patent is incorporatedherein by reference as part of the present-specification. -'-With the armature of repeating relay 8| disengaged from its markingcontact the circuit of selector magnet 82 of the teletypewri-ter printer is interrupted and the release of this electromagnet represents the start impulse of a telegraph code combination. As soon as the outer-brush leaves the short segment it passes overa dead segment and in so doing interrupts the circuit through the operating winding of deciphering relay 16 and through the locking winding of receiving relay 62.- Relay B2 is thus freed for response to the next received impulse but relay x'lfi-is .not disturbed because it remains locked to the spacing condition and'holds repeating-relay 8! in the spacing condition. i

In addition to the short segment following the rest segment, five transmitting contacts flli, which are engaged by their respective contact'le- .vers 39 when those levers are rocked to extreme clockwise position under the influence of thetape sensing levers in rocking to their extreme-counter-clockwise position to sense perforations in the tape, are connected over conductor -12 to the circuit branching point 13. Similarly, five other transmitting contacts 81 which are engaged by the transmitting contact levers 39 when those levers are in their counter-clockwise positions under the control of tape sensingglevers which do not find perforations in the tape, are connected to a circuit branching point 15 from which a path is traced through resistor 5'8 and a parallel path is traced through resis- .tor E7, the operating winding of relay 'lfi and resistor 14, these paths rejoining at the junction point 79. The five transmitting contact -1evers 3.9 are connected by five conductorstfi to five equa ly spaced short segments in the outer ring of the distributor and these segments represent the five significant impulses of a permutation code combination.

The manner in which relay 16 operates under the joint control of receiving relay 62 and the code combinations contained in tape '53 to derive the message signals, is fully described in the hereinbefore identified patent to K. E. Fitch and G. A. Locke and will not be repeated herein. It will be understood from the disclosure of that patent that during the reception by relay 62 of any ciphered code combination, if the tape sensing levers 36 are sensing the same code combination that was used in encipherin the ciphered code will be correctly deciphered and the impulses representing the message signal will be repeated by relay 8| to the selector magnet 82 of the teletypewriter printer.

Shortly after shaft I3 is released for rotation in the manner hereinbefore described, the apex of cam 23 moves away from lever 24, the lever is rocked in clockwise direction by its spring 21', retracting the abutment screw 28 and permitting spring 33 to rock bail 3| in clockwise direction. With the bail rocked in this direction springs 43 rock tape sensing levers 36 in counterclockwise direction to sense the code combination of perforations in the tape and spring 46 rocks tape feed lever 43 in counter-clockwise direction, moving pawl 4'! upwardly to pick up the next tooth on ratchet 48. As shaft l3 nears completion of one revolution the apex of cam 23 again engages lever 24, restoring lever 24, ball 31, tape sensing levers 36 and tape feed lever 43' to the condition shown in the drawing. Tape feed. lever 43, in being rocked to its extreme clockwise position, rotates ratchet 48 one step the direction indicated by the arrow, thereby advancing the next combination of perforations .in tape 53 to thetape sensing position.

Just before the brushes of the distributor reach the rest segment, the outer brush passes over a short segment which'is connected over conductors H and 12 to the branching point .13. The speed of rotation of the distributor is such that receiving relay 62 is receiving the stop impulse at the end of the received code combination at the time that the brush passes over .marking if it had not already been operated to this condition prior to reception of the stop impulse, and the marking signal represented by this .condition of relay 16 is repeated by relay 8I to the selector magnet 82 of the teletypewriter printer. As the brushes move on to the rest segment they reconnect electromagnet 22 to the armature of receiving relay 6|. Since this relay is now in the marking condition there are like polarities at both ends of the circuit, electromagnet 22 remains released and lever 2| arrests distributor shaft disc I9. The distributor remains at rest until the armature of relay 62 again moves from its marking to its spacing contact.

If the next excursion of the armature of receiving relay 62 away from its marking contact is in response to the start impulse of a received code combination that code combination will .be received and deciphered. If it should not be in response to the start impulse of a code combination but should be in response to a hit or line surge or static burst which momentarily operates relay 62 out of the marking condition, electromagnet 68 will be energized, distributor shaft I3 -will be released for rotation and the distributor will execute at least one cycle of operation. At the end of this cycle tape 53 will be advanced one step and if no code combination is received during this cycle the distributor will stop at the end of the cycle and tape 53 will be one step ahead of the enciphering tape at the transmitting station. If a code combination is received while the distributor is partway through the erroneously started cycle, and code combinations continue to be received, it may be several cycles of the distributor before it is brought back into step with the received start and stop impulses and tape 53 may gain one or more additional steps on the enciphering tape at the transmitting station. With tape 53 out of step with the enciphering tape, code combinations thereafter received by relay 62 will not be correctly deciphered until tape 53 is brought back into step with the-enciphering tape. Since tape 53 is ahead of the enciphering tape, it may be brought back into correct phase with the enciphering tape by suppressing one or more tape feeding operations.

' Apparatus in accordance with the present invention for suppressing tape feeding operation includes a mounting plate IOI' which is attached to:a portion ofthe frame'of the transmitter? distributor represented fragmentally at I02. Mounting plate IOI has secured thereto a bracket 103 provided with slots for guiding theshank I04 of a push-button I06 which projects-outside the housinglnot shown) of the transmitterdistributor mechanism. "A spring I01 interconnects mounting plate II and the shank I04 of push-button I06 and exerts its pull on the shank I04 of push-button I06 in such direction that it not only retracts the push-button but holds it in engagement with the left-hand edges of its guide slots. I r

On its left-hand edge the shank of push-button I06 is provided with a cam projection I08, the purpose of which is to cause theshank I04 of the push -button, after it has been moved inwardly a predetermined distance by finger pressure on push-button I06, to move angularly so that its inner end moves rightwardly as the push-button continues to move inwardly. For this purposea small amount of freedom is provided between the shank I04 of the push-button and its outer guide slot'and considerably more lateral freedom is.

provided by the inner guide slot.

A leftwardlyextending projection H5 at the inner end of push-button shank I04 engages a pin I-09'carried by lever IIO, pivoted at III. A

latching lever II2 for the lever H0 is pivoted at H3, .and has a latching projection II4 disposed adjacent to the end of lever IIO which carries the pin- I09. When push-button I06 is depressed, the laterally extending projection at-the inner end of push-button shank I04, engaging pin I09, rocks lever H0 in clockwise direction and about the time that the end of lever I I0 clears latching projection H4 and a spring II6 rocks the latchinglever into latching relation to lever IIO, cam projection I08 moves push-button shank I04 laterally and disengages the projection I I5 at the inner end of the shank from pin I09. If push--v button I06 is then released spring I01 will restore it to its initial condition, lever IIO remaining latched. If push-button I06 is held in the operatedcondition the laterally extending projection at its inner end will be disposed rightwardly and out of cooperation with pin I09.

The arm of lever IIO which is disposed on the opposite side of pivot I I I from that which carries pin I09 is providedwith a spring post II1 from which a tension spring II8 extends to a spring post II9 secured to mounting plate IOI. Spring post II1 also has connected thereto one end of a tension spring I20 the other end of which is connected to a tape feed blocking lever I2I also pivoted at II I. Lever I2I is provided at its lefthand end as'viewed in the drawings with a shoulder I 22 which is adapted to block depending arm 44 of tape feed lever 43 under circumstances which will be described hereinafter. Lever I2I is also provided with a downwardly extending abutment I23 which is held against the right-hand edgecf the rearwardly extending arm of lever IIO by spring I20. 7

Bail 3I has attached thereto a bracket I24 to which is pivotally connected an unlatching bar I26 for the latching lever I I2. Blocking lever I2I is provided with a laterally extending arm I21 presented toward unlatching bar I26 and a spring I30 connected between bracket I24 and unlatching bar I26 holds the unlatching bar in engagement with the free end of arm I21 of tape feed blocking. lever I2I. A bracket I28 secured to mounting plate IOI serves as a guide for the outer edge of unlatching bar, I26 and the bracket I28 acre-n85 has, a portion overlying unlatching bar I26 to hold the unlatch n :bar substantially in slidable enga ement "with mounting plate III-I. There must be sufiicient freedom in the pivotal connectionbetweenunlatching bar I26 and bracket I24 carriedbybail 3 :I,to permit unlatch-ing bar; I26 to slide in a plane parallel to the plane of mountingplate- Hil as bail 3i :rocks' on its pivot 32. Bracket I28 determines the extreme clockwise angular position of unlatching bar I26 in its plane of movement; Laterally extending arm I21 of tape feed blocking lever I2 I, being in engagement with; unlatching, bar I2 6, determines the extreme counter-clockwise position of blocking leverv I2I. Abutment, I23 of blocking lever I2I determines the extreme counter-clockwise position of lever- I-Iii and spring IIB, being connected to lever I I 0, urges all of these elements into the extreme positions. In this condition of the apparatus a hook portion I29-of unlatching bar I26 is held clear of the :free end of latching lever II2. Whenthe cipher signal. generator is in operation to decipher incoming signals and push-button I06 is unoper-- ated unlatching bar I216 will slide back andforth in engagement with bracket. I26 and without engaging. its, hook. portion I29 with latching lever II 2.. In this. condition of the apparatus tape feed blocking lever I21 is held clear of the depending arm. 44 of tape feed lever 43 and this lever operates normally under the control of bail 3I.

Consideration will first be given to the sequence of. operations resulting from the depression of push-button I06 at a time when the cipher signal generator is idle. For example, if signals are not being received but an attendant hears or observes that the receiving. teletypewriter has executed an operating cycle; he will know that receiving relay 62 has responded to some extraneous condition simulating a start impulse and that the. deciphering signal generator has executed one cycle concurrently with the receiving teletypewriter, thereby causing the tape 53 to be one step ahead of the key tape atthe transmitting station. In order toin-itiate a. tape feed suppression operation for the purpose-of bringing tape 5.3 back into phase with the key tape at the transmitting station, the attendant operates push-button I 66. Shank I04 of. thepush-button rocks lever III] in clockwise direction and before the push-button shankbecomes disengaged from pin I09 due to the lateral camming of the push-button. shank .moves immediately into blocking relation to de--- pending arm-44 oi -tape feed lever 43. With lever I 2I thus rocked clockwise the free end of its laterally extending arm I21 is drawn away from unlatching bar 12E, permitting. that bar to rock in counter-clockwise directionabout its pivotal mounting on bracket I24; and under theinfluence of spring J30 until its h'ook'portion I29 engages the fr'ee'endof latching lever II2. When push:

' button I06-is released it returns to its normal condition without in any way disturbing the latched condition of lever I I0.

' Nothing further will happen until, in response to a received signal combination or to another line disturbance or atmospheric disturbance, simulating a start. impulse, another-cycle of the distributor ensues. At the beginningof such cycle, cam 23 permits bail 3I= to rock to its extreme clockwise position but the depending arm 44. of tape feed lever 43-is prevented from following the bail due to the blocking action or lever I2 I' and tape feed lever 43 does not rock in counter-clockwise direction to pick upthe next tooth on ratchet 48. Unlatching bar I26 moves rightwardly-as viewed inthe drawing, as bail 3| rocks to its extreme clockwise position and before the bar I26 reaches itslimitof movement its hook portion I29 escapes'from the free end of lever H2 and engages the rightedg-e of that lever, spring, I30 rocking bar I26 into operative engagement, with latching lever I I2.

As the distributor approaches completion of its cycle cam 23 restores bail 3| to near itsextreme counter-clockwise position. Unlatching bar I26 moves leftwardly with bail 3I- and in so doing rocks latchinglever. H2 inclockwise direction, releasing lever IIO from latching projection H4; Spring II8 immediately rocks lever H0 in counter-clockwise direction, lever H0 imparts counter-clockwise movement to lever I-2I through; abutment I23, thuswithdrawing lever IflI from blocking" relation to tape feedlever 43-, and the laterally extending arm I2-I of lever I2I rocks unlatching bar I-26 in clockwise direction, moving it out of operative relation-to latching lever- H2,

these various movements being arrested when" the distributor just describedhas also resulted.

from a disturbance in-thenommunication chant nel and the attendant is aware of it, he-may again operate pusha-button- I06, thereby to cause the feeding of tape to be suppressed-at the end of the next cycle of the distributor at suchtime as that next cycle occurs.

As previously set forth, a disturbance on the communication channel may occur while-message reception is in progress and cause tape 53 to gain one step on the keytape at the transmitting station. The material thereafter recorded will be unintelligible until the necessary correction is made. If the reception of the message is being closely supervised,.the attendant may operate push-button I06, almost as soon-as the out-ofphase condition of the tape-occurs, because the recording of two or three characters which do not fit the preceding portion of themessage and.

do not make sense is sufiicient to indicate the out-of-phase condition of the tape. The distributor may be at any point in its cycle at the time push-button I 06 is operated and for the pure poses of this description itwill be assumed that cam 23 has previously released bail 3I to itsv extreme clockwise position. I As before, lever [I0 isrocked inclockwise direction by pushbutton' I06 and becomes latched by lever- II-2. Blocking lever I2I starts to follow-the movement of lever III) but blockingshoulder I22 of lever IZ'I is's'o located. that it can move into. blockingv relation to depending arm 44 of tape feed-lever 43 only when thatlever is iii-substantially theextreme clockwise-position. Since the tape feed lever o d be in I the extreme. countereclockwise posit This engagement arrests lever |2| while lever I I continues to its latched position under the operative influence of push-button I06, spring I I9 yielding to accommodate the full movement of lever I III. With bail 3| in the extreme clockwise position the hook portion I29 of unlatching bar I26 is disposed to the right of the free end of latching lever 2 but the small amount of movement that the depending arm-44 of tape feed lever 43 has permitted to blocking lever 2| in turn limits the counter-clockwise movement permitted to unlatching bar I26 by projection I21 of lever |2| and this movement is insufilcient to bring the hook portion |29of bar I26 into operative relation to latch lever H2. Accordingly, a condition preparatory to the blocking of tape feed lever 43 is stored in spring I 20.

As the distributor approaches completion of its cycle cam 23 restores bail 3| to extreme counterclockwise position. Bar I26 is retracted by bail 3| without engaging and releasing latch lever H2. Tape feed lever 43 is rocked in clockwise direction by bail 3|, thus advancing ratchet 48 one step and advancing the next code combination in tape 53 to the sensing position. As tape feed lever 43 approaches its extreme clockwise position its depending arm 44 moves to the right of blocking shoulder I22 on lever |2| and when this occurs the energy stored in spring I|9 rocks lever I2| into full blocking relation to depending arm 44 of tape feed lever 43. In so doing, lever |-2| withdraws the end of its laterally extending arm I 21 away from unlatching bar I26, preparing that bar to engage and release latch II 2. Assuming that another receiving cycle ensues immediately, bail 3| will rock to extreme clockwise position bringing unlatching bar I26 into operative relation to latching lever 2. Tape feed lever 43 is held by blocking lever |2| and is prevented from picking up the next tooth. The code combination 'just previously brought to the sensing position will be'se'nsed by tape sensing levers 36 and the impulses represented thereby will interact with the impulses of the received code combination. This received code combination will not be correctly deciphered because the code combination in the key tape 53 is now being sensed for the first time. As the distributor completes its cycle bail 3| is returned to its extreme counter-clockwise position. This ordinarily is used to perform the tape feeding operation but since the tape feed lever has been blocked and held from picking up the next tooth in the ratchet 48'. the tape is not advanced. The return of bail 3| to its extreme counter-clockwise position results in the release of latch ||2 through the'operation of releasing bar I26 and the tape feed suppression mechanism is restored to normal condition. In the next receiving cycle of the distributor the impulses of the same code combination in key tape 53 :interact with the received impulses. Since the key tape has not advanced Whereas the key tape at the transmitting station presumably has advanced, the two key tapes should now be in phase and the code combination should be correctly deciphered.

If the teletypewriter continues to print unintelligible material it will probably be a result of the gaining by tape 53 of two or more steps on the-key tape at the transmitting station. Ac-' cordingly, the attendant will again operate pushbutton- |06 to suppress feedingof the t pe by movement aneste relative to t e cycl s-6r the distributoii and if this does not produce intelligible copy he may operate push-button I06 still anothe'r timel In all likelihood'the tape-53 will not-gain more than one or twosteps 'onthe tape atfthe trans mitting station and'only a few operations got push-button I06 will be required toeiifek it tl'ie necessary correction. Because ofthe non re-i peat characteristic of push-button I06 afforded by its cam projection "I08, feeding of tape 53' will be suppressed for only one cycle ofthe distributor for each separate operation of push-button I 06-re'gardless of how long the attendant holds the push-button operated.' In this way rephasing of the tape by single corrective steps is achieved. V A

Although a particular embodiment-0f the invention has been disclosed in the drawing and described in the foregoing specification it will be understood that the invention is not limited to such specific embodiment but is capable of modification and rearrangement without departing from the spiritof the invention and within the scope of the appended claims. I

What is claimed is: V

L 1. In a tape-controlled telegraph transmitter,

a distributor, a tape sensing mechanism, a tape feeding mechanism, means'for blocking said tape feeding mechanism, manually operable means for operating said blocking means, means for latching. said blocking means in its blocking condition,and means controlledby said distributor for releasing said latching means.

2. Ina tape-controlled telegraph transmitter, a distributor, a tape sensing mechanism, a tape feeding mechanism, means for blocking said tape feeding mechanism, manually operable means for operating said blocking means, means for latching said blocking means in its blocking condition, and means for precluding reoperation of said blocking meansexcept after restoration of said manually operable means to normal.

3. In a tape-controlled telegraph transmitter, a. distributor, a tape sensin mechanism, a tape feeding mechanism, means for blocking said tape feeding jm'echanism, manually operable means for activating said blocking means, means controlled by said distributor for'deactivating said blocking means, andmeans for precluding reactivation of said blocking'means except by restoration and reoperation able means. 1

4. In a tape-controlled telegraph transmitter,

a distributorfa. tape sensing mechanism, a tape feeding mechanism, a bail operable by said distributor for operating said tape sensing and tape feedin mechanisms, means for. blocking saidv tape feeding mechanism, .manually. operable means for activatingpsaid blocking means, means operable'by said bail for deactivating said blocking -means, and means; for precluding .reactiva: tion of said'bfocking means except by restoration and reoperation of said manually operable means,

1 REFERENCES CITED The following references are of record 3 in the file of this patent:

of said manually oper- 1 EDWARD r. wA'rsoN. 4 I 

